Coupling and brake combination

ABSTRACT

A brake coupling combination for a motor, preferably an electric motor, consisting of a brake which can be attached to the motor, the brake having a flange ( 1 ) with which it is directly connected to a correspondingly shaped part of the motor, characterized in that the brake is mounted on the end of the shaft ( 9 ) of the motor by means of a hub ( 4 ) and that a flexible coupling (K) connects directly to the brake for connection to a second shaft.

[0001] Safety brakes which release upon the application of an electriccurrent and which operate by means of spring pressure when the currentis removed, are in general known. They are usually mounted on the rearside of the motor, generally an electric motor, on the so-calledB-bearing side.

[0002] In countless technical installations for example lifts, it isrequired by the regulations to include a safety brake which in the eventof a fault for example, a power cut, immediately brings the system to astandstill, and holds it in this condition until the fault has beenrepaired. The inclusion of such brakes means additional installationwork, and requires more space.

[0003] Flexible bellow couplings that are stiff in the rotationaldirection, are known for connecting two shafts. They are mainlyinstalled between an electric motor and a drive coupling, workingmachine, spindle or the like.

[0004] The object of the present innovation is to unite a coupling and abrake into a unit, a so-called brake coupling combination in such a waythat this unit can be mounted in a simple manner on the drive side of anelectric motor (A-bearing side). The aim is in particular, to reduce thework and space requirement. Additionally, costs need to be saved,reliability increased, ease of servicing improved. Preferably thearrangement should be able to compensate for a high degree ofmisalignment between drive and driven shafts.

[0005] This task is solved by the fact that the hub of the brake, whichtransmits the angular momentum of the shaft to the brake, is constructedso that it forms at the same time the drive side of the output coupling,which preferably is a flexible bellows coupling. The second side of thecoupling transfers the angular momentum to the second shaft. With thisarrangement space is saved in the axial direction. The stiffness torotation of a bellows coupling can absorb at the same time axial, radialand angular misalignment. Further, the housing of the safety brake maybe constructed in a generally rectangular shape, so that the usual shapeof electric servomotors is preserved. By mounting the brake on the drivemotor shaft rather that on the rear end of the motor an improvement insafety is achieved. For example if the brake hub becomes disconnectedfrom the motor shaft due to a mechanical failure, in the arrangement ofthe invention, the drive becomes disconnected too. This is a “fail-safe”situation, and is due to the fact that the drive passes from the motorshaft to the drive external equipment via the brake hub.

[0006] An exemplary embodiment of a brake coupling combination, inaccordance with the invention will now be described with reference tothe drawings in which:

[0007]FIG. 1 shows a simplified elevation of the coupling-brakecombination;

[0008]FIG. 2 shows a cross-section on the line A-A in FIG. 1 and showsmore detail;

[0009]FIG. 3 shows an exploded partly cross sectional view showingcoupling of the coupling brake combination to the motor shaft; and

[0010]FIG. 4 shows a spring clip for use in the arrangement of FIGS.1-3.

[0011] Referring to FIG. 2, a brake-coupling combination is intended tobe flanged or screwed on to an electric motor 16 at the A bearing sidei.e. the end from which the drive shaft emerges. In FIG. 2 the motorshaft is shown, with the reference numeral 9. The brake couplingcombination essentially consists of a brake assembly 18 and a couplingassembly 19. The brake possesses a square flange 1, with which it isscrewed to a correspondingly shaped part, for example to the A-bearingcase of a servomotor, or the motor housing. The flange 1 serves at thesame time as a housing for the brake, and accommodates the manyindividual parts thereof. Typically the brake coupling assembly isbolted onto the motor 16 by four bolts, one of which passes through bore17. The bolts are not shown in FIG. 2.

[0012] The brake assembly 18 itself consists of an electromagnet coil 2;an armature plate 3; a hub 4 with a partially axially slit tube-likeextension 20, the hub 4 is connected to the motor shaft 9 such thatrelative rotation is not possible. This may be achieved for example byuse of a key in a keyway, or other conventional means such as a taper orcross pin.

[0013] The brake also includes at least one brake disk 5 which islongitudinally displaceable with respect to the hub 4 but which isconnected to it such as to turn with it. The brake disk 5 is sandwichedbetween the armature plate 3 and a flange plate 13 which islongitudinally fixed with respect to the housing of the brake. Brakepads 6 are mounted on either the brake disk itself or on the surfaces ofthe armature and flange plate facing it to increase friction betweenthese components. Typically the hub 4 carries on its outercircumference, splines which engage inwardly facing teeth on a boss inthe centre of the brake disk 5. The brake assembly 18 also has at leasttwo brake pads 6, disposed on the two sides of the brake disk 5. Thebrake also includes a plurality of guide pins 7 disposed and equallydistributed around the circumference to ensure good alignment of themoving parts in operation. Springs 8 also disposed and equallydistributed around the circumference urge the armature plate towards theflange plate, and hence into the braking condition. The brake pads 6 maybe fixed to the brake disk, so as to engage the inwardly facing surfacesof the armature plate 3, and a flange plate 13 on the other side of thebrake disk 5. Alternatively the brake pads can be on the mutually facingsurfaces of the armature plate 3 and the flange plate 13.

[0014] The shaft 9 of the motor 16 passes through the hub 4 includingthe partially axially slit tube-like extension 20 and into the couplingunit 19 of the coupling brake combination.

[0015] The coupling unit 19 couples the motor drive shaft 9 with adriven shaft 12 connecting to other machines and consists of flexiblebellows 11 (preferably made of metal), by a locking ring 10 b lockedonto the motor shaft 9 via the tube-shaped axially slit extension 20 ofthe hub 4 at one end and on a correspondingly adapted coupling hub 14that is in turn locked onto a driven shaft 12, at the other end.

[0016] The flange plate 13 as well as holding the brake together, andproviding the reaction force, also offers the possible connection ofdrive transmission by means of a centering adjustment 15.

[0017] In operation, when the electromagnet coil 2 is excited itattracts the armature plate 3 thereby pulling the armature plate 3 awayfrom the brake disk. Once there is no longer any frictional contactbetween the armature plate 3, the brake disk 5, the brake pads 6 and theflange plate 13 there is no braking effect. If the electricity supply tothe electromagnet coil 2 is interrupted, the armature plate 3 isreleased, and is immediately moved in the direction of the brake disk 5and flange plate 13, by the springs 8. As the brake disk 5 is free tomove longitudially on the splines on the hub 4, it moves in thedirection of the flange plate 13, balancing the braking effect on thetwo sides of the brake disk.

[0018] The flexible bellows 11 are movable in all directions and cancompensate for any kind of misalignment of the shafts, axial, radial andangular. By the attachment by the locking rings 10 or 10′ (radially slitand clamped by a screw not shown in more detail), the flexible bellows11 can be secured on the short end of the shaft so that space can besaved. The locking rings 10, 10′ in addition, achieve a locking of thebellows and the locking between the hub 4 and the drive shaft 9 on theone hand, and the coupling hub 14 and the drive shaft 12 on the otherhand

[0019] Referring to FIG. 3, there is shown an exploded view of a portionof the coupling and brake combination. The same or corresponding partshave been given the same reference numerals as in FIGS. 1 and 2. FIG. 3shows a motor shaft 9, and a hub 4 which supports a brake disk (notshown). The hub 4 is sized to fit on the motor shaft 9 and has key-ways(not shown) to prevent mutual rotation between the shaft 9 and the hub4. The hub 4 has a longitudinally extending cylindrical sleeve portion20 which has one or more longitudinal slits 23. It also has an outwardlyfacing annular groove 21 in its outer cylindrical surface. A metalbellows assembly 11 has a generally cylindrical right hand-end 26 sizedto fit over the left-hand end of the cylindrical sleeve forming theextension 20 of the hub 4. The metal bellows assembly 11 is held inplace on the extension 20 of the hub 4 by means of a locking ring 10 bsized to fit around the cylindrical end 26 of the metal bellows 11. Thelocking ring 10 b has an inwardly facing annular groove 22 in its innersurface, to receive a spring clip 25. The spring clip 25 is shown inFIG. 4. As it is located in the annular groove 22, as the locking ring10 b is passed over the sleeve 20, but before it is tightened down, thespring clip 25 comes to rest in the outwardly facing annular groove 21.This serves to locate the locking ring 10 b on the sleeve 20.

[0020] The locking ring 10 b has a radial split or slot with atangential bolt 24 passing across it. When the locking ring 10 b isassembled and in place around the cylindrical end 26 to the metalbellows assembly 11, which in turn is in place on the cylindricalextension 20 of the hub 4, the bolt 24 can be tightened. This urges theradial slot in the locking ring 10 b closed, which causes the ring togrip the cylindrical extension 26 of the metal bellows 11 against theouter surface of the extension 20 of the hub 4. The tightening alsotends to urge the slot 23 in the cylindrical sleeve 20 of the hub 4 in aclosing direction, thereby causing the hub 4 to grip tightly against themotor shaft 9. Accordingly, the locking ring 10 b serves a dual functionof holding the metal bellows 11 to the brake hub 4 and also holding thebrake hub 4 to the motor shaft 9. This is particularly advantageousbecause it dispenses with the need to provide a separate fixing means toprevent longitudinal movement of the brake hub 4 with respect to themotor shaft 9. The result is that the flexible coupling can be mountedcloser to the motor. This is particularly advantageous in situationswhere there is a limited amount of available motor shaft, or a limitedamount of space for the entire assembly. Such situations are common whena brake is being retrofitted to an existing installation. The couplingand brake combination in accordance with the present invention thereforsaves a considerable amount of space and allows braking assemblies to beretrofitted to motors in spaces which were previously considered toosmall.

1. A coupling and brake combination for a motor, preferably an electricmotor, the brake having a flange (1) for directly connecting thecombination to the correspondingly shaped part of the motor housing,characterized in that the brake is attached by means of a hub (4) on themotor shaft (9) of the motor, and that the hub (4) connects directly toa coupling (11) for transmission of motor rotation to a second shaft. 2.A combination according to claim 1 characterized in that the coupling(11) is a metal bellows coupling.
 3. A combination according to claim 2characterized in that the metal bellows coupling is non-rotatablyconnected to the end of the shaft (9) by means of a locking ring (10 b).4. A combination according to claim 3 characterized in that the lockingring (10 b) simultaneously clamps the flexible metal bellows (11) andthe hub (4) to the motor shaft (9).
 5. A combination according to any ofclaim 2, 3 and 4 characterized in that the end of the flexible metalbellows (11) remote from the motor shaft (9) is clamped to a secondshaft (12) by being sandwiched between a split sleeve mounted on theshaft and a split locking ring (10 a) clamping down on the outercircumference of the end of the said remote end of the bellows.
 6. Acombination in accordance with any preceding claim characterized in thatthe flange (1) comprises a housing accommodating the various componentsof the brake.
 7. A combination in accordance with any preceding claimcharacterized in that the brake consists of an electromagnet coil (2),an armature plate (3), the hub (4), at least one brake disk (5), atleast two brake pads (6) and at least one spring (8) that presses thearmature plate (3) in the braking direction.
 8. A combination inaccordance with any preceding claims characterized in that the flange(1) is rectangular preferably square.
 9. A combination according to anypreceding claim characterized in that the hub (4) of the brake isdirectly mounted on the motor shaft (9) and is provided with anoutwardly axially projecting tube-like slotted projection (20) alsomounted directly on the motor shaft (9), wherein the flexible coupling(11) has a cylindrical gripping end which is mounted over the axiallyprojecting tube-like slotted projection (20), a locking ring (10 b)being provided to hold the cylindrical gripping end of the flexiblecoupling to the projection (20) and simultaneously hold the projection(20) to the motor shaft, (9).
 10. A method of retrofitting an electricmotor by installing a brake and coupling combination in accordance withany preceding claim to the A bearing side of the motor.